Allowing OTA to be managed more freely.

[UltimateMaker]

I have an esp32 4MB, and have fulled the memory by adding various libraries, bt, webserver, OTA etc. I do not want to get rid any of these in my project but in order to have them all fitted i had to do something so i came to this solution. Create a partition that has unequal OTA0 and OTA1. So this is how it works.

My main project is like 2051015. Max partition i could create was 2031616 having two mirror OTA 0 OTA 1. so i created a second sketch, bare bones, just OTA so it does not take much space but i also created a custom made partition where OTA 0 is smaller than OTA 1. Uploaded the small sketch first using the OTA 0 and then using OTA i uploaded my main sketch using OTA 1. Every time i have to upload my main, i have to upload the small sketch and then the main big one. It is kinda tiring but it works and creates the required space :).

So an the ability that would allow to create unequal partitions for ota on demand would be great!

[thelastoutpostworkshop]

This now available in the new version (1.2.4), please test it.

[UltimateMaker]

For example having an empty table, click add partition, select OTA, then enable the allow unequal OTA slots. Then on the ota_1 click to reclaim the memory. ota_0 is 65536 and ota_1 4063232. All memory looks like it is used but if you see on the top bar where you can see where each partition starts and ends you will see that there are 8kb of unused free space. If there is an alignment issue on the addresses where that 8kb cant be used by ota, at least the NVS or another partition should be able to use it. The moment i reclaim the ota_1 it says Available Flash Memory:
0 bytes (0 KB)
while there is 8kb of unused free space. If then i go to nvs click the + button two times it adds those 8kb there 4+4 and the
Available Flash Memory:
0 bytes (0 KB)
did not change at all while i was adding memory to nvs. It needs to update on every action. If i click + 3 times then it kinda crash because it exceeds and does random stuff.

[UltimateMaker]

This is for example how it would work.
You can include it as example and can remove parts like the webserver or AP to reduce size.

It has a webserver where you can upload .bin files. You can upload files from the IDE via network. A network where it connects to or connect to its own access point and then update. In case you have uploaded and it shows that you are on ota 1 then you need to upload it again so it goes to ota 0 then you can upload your main program no issue

You will need first to compile via cable, see the size of this sketch for ota 0, then create the partitions table based on that. The rest can be your main project / nvs

// ============================================================================
// ESP32 General OTA Staging & Partition Helper
//
// Features:
//   1. Displays current running OTA partition (ota_0 / ota_1)
//   2. Connects to STA (using NVS creds or defaults) with AP fallback
//   3. Web GUI to upload a .bin file directly into the inactive OTA slot
//   4. Web endpoints to inspect partition status and manually switch boot partitions
//   5. Classic ArduinoOTA handler for updating this helper over the network
// ============================================================================

#include <WiFi.h>
#include <WebServer.h>
#include <Update.h>
#include <ArduinoOTA.h>
#include <ESPmDNS.h>
#include <Preferences.h>
#include "esp_ota_ops.h"

// ============================================================================
// CONFIGURATION
// ============================================================================

// --- WiFi Configuration ---
const char* DEFAULT_STA_SSID     = "YOUR_WIFI_SSID";
const char* DEFAULT_STA_PASSWORD = "YOUR_WIFI_PASSWORD";

const char* AP_SSID             = "ESP32_Staging_AP";
const char* AP_PASSWORD         = "12345678";

// --- OTA & Network Identity ---
const char* MDNS_HOSTNAME       = "esp32-updater";
const char* ARDUINO_OTA_PASS    = "admin123";

// --- Global Objects & Variables ---
WebServer   server(80);
Preferences preferences;

bool updateAborted = false;
int  wifiRetryCount = 0;
const int MAX_WIFI_RETRIES = 5;
const unsigned long WIFI_RETRY_INTERVAL = 10000; // 10 seconds

// ============================================================================
// NVS UTILITIES
// ============================================================================
String loadWiFiSSIDFromNVS() {
  preferences.begin("wifi", true);
  String ssid = preferences.getString("ssid", "");
  preferences.end();
  return ssid;
}

String loadWiFiPasswordFromNVS() {
  preferences.begin("wifi", true);
  String pass = preferences.getString("pass", "");
  preferences.end();
  return pass;
}

// ============================================================================
// PARTITION HELPERS
// ============================================================================
void printRunningPartition() {
  const esp_partition_t* running = esp_ota_get_running_partition();
  Serial.printf("🔎 Running partition: %s (Offset: 0x%06X, Size: 0x%06X)\n", 
                running->label, running->address, running->size);
}

String getRunningPartitionLabel() {
  const esp_partition_t* running = esp_ota_get_running_partition();
  return String(running->label);
}

// ============================================================================
// NETWORKING
// ============================================================================
bool connectToWiFiSTA() {
  String sta_ssid = loadWiFiSSIDFromNVS();
  String sta_pass = loadWiFiPasswordFromNVS();
  
  if (sta_ssid.length() == 0) {
    sta_ssid = DEFAULT_STA_SSID;
    sta_pass = DEFAULT_STA_PASSWORD;
    Serial.println("ℹ️ No NVS WiFi credentials found, using defaults.");
  }

  Serial.printf("Connecting to STA: %s\n", sta_ssid.c_str());
  WiFi.begin(sta_ssid.c_str(), sta_pass.c_str());

  int retry = 0;
  while (WiFi.status() != WL_CONNECTED && retry < 20) {
    delay(500);
    Serial.print(".");
    retry++;
  }

  if (WiFi.status() == WL_CONNECTED) {
    Serial.printf("\n✅ STA Connected! IP: %s\n", WiFi.localIP().toString().c_str());
    wifiRetryCount = 0;
    return true;
  } else {
    Serial.println("\n⚠️ STA Connection failed.");
    return false;
  }
}

void setup_wifi() {
  WiFi.mode(WIFI_STA);
  bool staConnected = connectToWiFiSTA();
  
  if (!staConnected) {
    Serial.println("⚠️ Starting Access Point mode...");
    WiFi.mode(WIFI_AP);
  } else {
    WiFi.mode(WIFI_AP_STA);
  }
  
  if (WiFi.softAP(AP_SSID, AP_PASSWORD)) {
    Serial.printf("✅ AP Active: %s | IP: %s\n", AP_SSID, WiFi.softAPIP().toString().c_str());
  } else {
    Serial.println("❌ Failed to start AP!");
  }
}

void setup_mdns_and_arduino_ota() {
  if (MDNS.begin(MDNS_HOSTNAME)) {
    Serial.printf("📡 mDNS responder started: http://%s.local\n", MDNS_HOSTNAME);
  }

  ArduinoOTA.setHostname(MDNS_HOSTNAME);
  ArduinoOTA.setPassword(ARDUINO_OTA_PASS);

  ArduinoOTA.onStart([]() { Serial.println("🔥 ArduinoOTA update starting..."); });
  ArduinoOTA.onEnd([]()   { Serial.println("✅ ArduinoOTA update complete, rebooting..."); });
  ArduinoOTA.onError([](ota_error_t error) { Serial.printf("❌ ArduinoOTA Error [%u]\n", error); });

  ArduinoOTA.begin();
  MDNS.addService("http", "tcp", 80);
}

// ============================================================================
// OTA WEB HANDLERS
// ============================================================================
void handleSwitchPartition() {
  const esp_partition_t* running = esp_ota_get_running_partition();
  const esp_partition_t* next    = esp_ota_get_next_update_partition(NULL);
  
  if (next == NULL) {
    server.send(500, "text/plain", "❌ No target OTA partition found!");
    return;
  }
  
  uint8_t test[4];
  esp_err_t err = esp_partition_read(next, 0, test, 4);
  if (err != ESP_OK) {
    server.send(500, "text/plain", "❌ Unable to read target partition header.");
    return;
  }
  
  bool hasData = false;
  for (int i = 0; i < 4; i++) {
    if (test[i] != 0xFF) { hasData = true; break; }
  }
  
  if (!hasData) {
    server.send(500, "text/plain", "❌ Target partition appears unflashed/empty!");
    return;
  }
  
  err = esp_ota_set_boot_partition(next);
  if (err != ESP_OK) {
    server.send(500, "text/plain", "❌ Failed to set boot partition.");
    return;
  }
  
  String response = "✅ Boot partition set to " + String(next->label) + 
                    "\n🔄 Rebooting in 2 seconds...";
  server.send(200, "text/plain", response);
  
  delay(2000);
  ESP.restart();
}

void handlePartitionStatus() {
  const esp_partition_t* running = esp_ota_get_running_partition();
  const esp_partition_t* boot    = esp_ota_get_boot_partition();
  const esp_partition_t* next    = esp_ota_get_next_update_partition(NULL);
  
  String response = "=== OTA PARTITION STATUS ===\n";
  response += "Running Partition : " + String(running->label) + "\n";
  response += "Boot Partition    : " + String(boot->label) + "\n";
  
  if (next != NULL) {
    response += "Next Target       : " + String(next->label) + "\n";
    uint8_t test[4];
    if (esp_partition_read(next, 0, test, 4) == ESP_OK) {
      bool hasData = false;
      for (int i = 0; i < 4; i++) {
        if (test[i] != 0xFF) { hasData = true; break; }
      }
      response += hasData ? "Target Status     : Valid Data Present\n" : "Target Status     : Empty (0xFF)\n";
    } else {
      response += "Target Status     : Read Error\n";
    }
  } else {
    response += "Next Target       : None\n";
  }
  
  server.send(200, "text/plain", response);
}

String buildUploadPage() {
  String running = getRunningPartitionLabel();
  bool inPrimarySlot = (running == "ota_0");
  String targetSlot  = inPrimarySlot ? "ota_1" : "ota_0";

  String banner =
    "<div style='background:#1e293b;border:1px solid #334155;border-radius:8px;padding:14px;margin:0 auto 20px;max-width:460px;'>"
    "Running from: <b style='color:#38bdf8;'>" + running + "</b><br>"
    "Next upload destination: <b style='color:#4ade80;'>" + targetSlot + "</b>"
    "</div>";

  String page =
    "<!DOCTYPE html><html><head><meta name='viewport' content='width=device-width, initial-scale=1'>"
    "<title>ESP32 OTA Staging</title>"
    "<style>"
    "body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;text-align:center;margin-top:40px;background:#0f172a;color:#f8fafc;}"
    "button{font-size:14px;padding:10px 18px;border:none;border-radius:6px;cursor:pointer;margin:5px;transition:0.2s;}"
    "button:hover{opacity:0.85;}"
    ".btn-primary{background:#2563eb;color:#fff;}"
    ".btn-secondary{background:#7c3aed;color:#fff;}"
    ".btn-dark{background:#334155;color:#f8fafc;}"
    "input[type=file]{margin:15px 0;}"
    "#bar{display:none;width:300px;height:16px;background:#1e293b;border-radius:8px;overflow:hidden;margin:20px auto;border:1px solid #475569;}"
    "#barFill{width:0%;height:100%;background:#22c55e;transition:width 0.1s;}"
    "</style></head><body>"
    "<h2>⚡ ESP32 Firmware Updater</h2>"
    + banner +
    "<input type='file' id='fileInput' accept='.bin'><br>"
    "<button class='btn-primary' onclick='doUpload()'>Upload Firmware</button>"
    "<div id='bar'><div id='barFill'></div></div>"
    "<p id='status'></p>"
    "<div style='margin-top:25px;'>"
    "<button class='btn-secondary' onclick='switchPartition()'>🔄 Switch Partition</button>"
    "<button class='btn-dark' onclick='showPartitionStatus()'>📊 View Status</button>"
    "</div>"
    "<div id='otaStatus' style='margin:15px auto;max-width:460px;text-align:left;background:#020617;padding:12px;border-radius:6px;font-family:monospace;font-size:12px;color:#38bdf8;display:none;white-space:pre-wrap;'></div>"
    "<script>"
    "function doUpload(){"
    "  var f = document.getElementById('fileInput').files[0];"
    "  if(!f){ document.getElementById('status').textContent='Select a .bin file first.'; return; }"
    "  var xhr = new XMLHttpRequest();"
    "  var data = new FormData();"
    "  data.append('update', f);"
    "  document.getElementById('bar').style.display='block';"
    "  document.getElementById('status').textContent='Uploading...';"
    "  xhr.upload.addEventListener('progress', function(e){"
    "    if(e.lengthComputable){"
    "      var pct = Math.round((e.loaded / e.total) * 100);"
    "      document.getElementById('barFill').style.width = pct + '%';"
    "      document.getElementById('status').textContent = 'Uploading... ' + pct + '%';"
    "    }"
    "  });"
    "  xhr.onload = function(){ document.getElementById('status').textContent = xhr.responseText; };"
    "  xhr.onerror = function(){ document.getElementById('status').textContent = 'Upload failed (connection reset).'; };"
    "  xhr.open('POST', '/update', true);"
    "  xhr.send(data);"
    "}"
    "function switchPartition(){"
    "  if(confirm('Switch active boot partition and restart?')){"
    "    document.getElementById('status').textContent = '🔄 Switching...';"
    "    fetch('/switchpartition').then(r=>r.text()).then(d=>{ document.getElementById('status').textContent = d; });"
    "  }"
    "}"
    "function showPartitionStatus(){"
    "  var el = document.getElementById('otaStatus');"
    "  if(el.style.display === 'block'){ el.style.display = 'none'; return; }"
    "  el.style.display = 'block'; el.textContent = 'Loading...';"
    "  fetch('/partitionstatus').then(r=>r.text()).then(d=>{ el.textContent = d; });"
    "}"
    "</script></body></html>";

  return page;
}

void setup_webserver() {
  server.on("/", HTTP_GET, []() {
    server.send(200, "text/html", buildUploadPage());
  });

  server.on("/switchpartition", HTTP_GET, handleSwitchPartition);
  server.on("/partitionstatus", HTTP_GET, handlePartitionStatus);

  server.on(
    "/update", HTTP_POST,
    []() {
      server.sendHeader("Connection", "close");
      if (updateAborted) {
        server.send(500, "text/plain", "FAIL - Flash aborted due to write errors.");
      } else if (Update.hasError()) {
        server.send(500, "text/plain", "FAIL - General flash memory error.");
      } else {
        server.send(200, "text/plain", "OK - Flash complete! Rebooting into new image...");
      }
      delay(500);
      ESP.restart();
    },
    []() {
      HTTPUpload& upload = server.upload();
      
      if (upload.status == UPLOAD_FILE_START) {
        Serial.printf("⬆️ OTA Upload Started: %s\n", upload.filename.c_str());
        if (!Update.begin(UPDATE_SIZE_UNKNOWN)) {
          Update.printError(Serial);
          updateAborted = true;
          return;
        }
        updateAborted = false;
        
      } else if (upload.status == UPLOAD_FILE_WRITE) {
        if (updateAborted) return;
        
        if (Update.write(upload.buf, upload.currentSize) != upload.currentSize) {
          Update.printError(Serial);
          updateAborted = true;
        }
        
      } else if (upload.status == UPLOAD_FILE_END) {
        if (updateAborted) return;
        if (!Update.end(true)) {
          Update.printError(Serial);
        } else {
          Serial.println("✅ OTA Upload Finished Successfully.");
        }
      }
    }
  );

  server.begin();
  Serial.println("🌐 HTTP Web Server running on port 80");
}

// ============================================================================
// MAIN SETUP & LOOP
// ============================================================================
void setup() {
  Serial.begin(115200);
  delay(500);

  printRunningPartition();
  setup_wifi();
  setup_mdns_and_arduino_ota();
  setup_webserver();
  
  Serial.println("\n--- ESP32 OTA Staging Helper Ready ---");
}

void loop() {
  ArduinoOTA.handle();
  server.handleClient();

  // Periodic WiFi Reconnect Check
  static unsigned long lastWiFiCheck = 0;
  unsigned long now = millis();
  
  if (now - lastWiFiCheck > WIFI_RETRY_INTERVAL) {
    lastWiFiCheck = now;
    if (WiFi.getMode() != WIFI_AP && WiFi.status() != WL_CONNECTED) {
      wifiRetryCount++;
      if (wifiRetryCount < MAX_WIFI_RETRIES) {
        connectToWiFiSTA();
      } else {
        Serial.println("❌ Max WiFi retries reached. Falling back to Access Point mode.");
        WiFi.mode(WIFI_AP);
        WiFi.softAP(AP_SSID, AP_PASSWORD);
      }
    }
  }
}

[thelastoutpostworkshop]

Fixed. Try version 1.2.5

[UltimateMaker]

In case the unequal ota is not used, then reclaim the full space to ota, there are 64kb of unused space. NVS could use that

[thelastoutpostworkshop]

Thanks for testing. When Allow unequal OTA slots is disabled, the two OTA partitions must remain the same size and aligned to 64 KB, which leaves 64 KB unused at the end of a 4 MB layout.
Would you like the builder to automatically move the NVS partition after the OTA slots and expand it into that remaining 64 KB? This would change NVS’s address, so it is best applied when creating/flashing a new partition layout rather than to preserve existing NVS data.

[UltimateMaker]

The best practice i think is to use all the space and nothing gets wasted. So if it is not an issue the NVS should be placed always at the end